Manual telephone system



July 24, 1928. 1,678,068

J. H. LEVIS, JR

MANUAL TELEPHONE SYSTEM Filed Dec. 2?", 1925 INVENTOR JOHN H. LEVlS JR.

BY WW'ITM ATTORNEY Patented July 24, 1928. c

PATENT err-ice.

.ioniki n; t'n vis, 33s., or socssmamw as esses- 1; r0 'r-nn SfIItOMBE-BQGARL- son TELEP ON irAnnrAorURIno COMPANY, on nocnns'rnn, NEW YORK, A 00R- POBATION or new YORK.

MANUAL 'rnnni noiin sY s'rnn.

Application filed December 23, 1925. Serial No. 77,197.

This invention relates to manualtelephone systems and more partici'ilarly to manualtelephone systems in which toll switching trunks are used.

This invention is nation of order wires in such atelephone system whereby the toll operator instead of being assigned a trunk by the terminating or B operator selects an idle trunk located at the terminating or B position. Means are provided in the form of a signal to the toll operator to inform her when a terminat ng operator is ready to receive the designation of the wanted telephone line. Th s and other features of thepresent nvention are accomplished by a special application oi the general methoddisclosed in my co-pending application, Serial No. 703,1di, filed December 1 192%.

One of the main ieatur s of the present c b c: invention is the novel method ol associating a terminating operators telephone set with a trunk circuit to which a toll line has been.

extended. a c z Another feature of this invention is tne circuit arrangement by which a set of keys, comprising one key for each source of ringing current, is common to a group oi trunk v 1! circuits and is arranged to (JO-DIDGIdiZG witn the circuits by which an operators telephone set is connected to a trunk circuit taken for use.

provision ol'nieansyby which theproper treqi'iency tor signalling. awanted telepi p ng line is selected by the terminating or ii operator, but is not ttPPllQClllO the wan-s ed telephone line upon connection therewith, until the ringing key at the toll operator s position is manually operated.

The drawings with Figs. 1 and 2 arranged in the order named, diagran'nnaticaily represent the circuits used in a 'toll switching system. In the upper left hand portion 01 Fig. 1 there is represented a calling subscribers substation, which is associated with the toll line. in order to simplify the drawings and since it is not believed necessary toshow the toll line circuit-s located at the distant exchange, the calling subscribers substation is shown connected to the toll line by dotted lines.

The toll line terminates on a jack J at the toll operators positionv The toll operators directed to the elimi Another feature otthis invention is the.

trunk extending from jack T. to the terminating or B position. These toll switching trunks may be mixed with other trunks located on regular B positions, but preferably they are segregated andlocated on special B positions. which are used for toll switching service only. v

At the right of Fig. 2 is shown a common battery substation ,B, connected to a multiple jack T In the upper-portion of Fig. 2 is shown a series of relays, which are common to a certain number of toll switching trunks, one particularly useful arrangement being the provision of one set of these common relays for twenty trunks. In the lower portion of F 2 is shbwn a series of six slow acting relays, associated with seven nonlocking buttons or keys.- One set ofthese re- 'meter are common to a certain number of toll switching trunks, one particular arrangement which has'been found desirable being the use of one set of these relays for ten trunks. i

It is believed that the invention will best be understood by describing the method of establishing a telephone connection from a calling subscriber A, whose line terminates at an exchange in one oflice with a subscribers line such as B, which terminates at a dis taut ofiice, such connection being established over toll line T. L. For the purpose of this description it will be assumed that substa- 'tion A. is of the local battery type and that it is connected to the tollline in any wellv known manner; for example, by meansojl. a cord circuit at a toll position in the distant exchange; The toll operator at the distant C. and the coming trunk, which is located on the toll board in the same exchange with which substation B is associated. Relay will be operated by ringing current and will close a circuit from grounchright hand back contact of relay 34., make contact oi. relay 35 and l t't hand winding of relay 85 to grounded britery. This circuit functions to lock relay 35 in its operated position. Lamp 11 is connected in multiple with the left hand winding of relay 35 and it is therefore lighted to give an indication to the local toll operator that a connection is desired to this particular toll line. The toll operator inserts the answering plug P into the jack J thereby closing a circuit over the sleeve of the plug and jack for operating relay'iid, which oatinguishes the signal 11.

- The local toll operator operates her listening key (not shown) and establishes a talking connection with the distant toll operator or subscriber A and determines the number oi the wanted subscriber. The local toll operator now inserts plug P into a toll switching trunk ack, for example T, thereby closing a circuit by way of the sleeve contacts oi the plug and ck connection to operate relays 38 and 39 in the well known manner. The operation of relay 89 connects a high wound impedance coil 10 cross tie tip and ring concltlctors of the toll switching trunk for a purpose to be described later. Relay 38 prepares a circuit from ground for lighting supervisory lamp 12, as will be pointed out in the following description.

A circuit is now closed for operating relay 1 of the toll switching trunk of 2, QX-x tending from grounded battery, right hand winning of relay 1, left hand continuity spring and back contact of relay 4-, upper winding of irepeed iirg coil, upper conductor of the total switching trunk, tip contacts the jack and plug, back contact of the toll operatofls ringing key, winding'o'f relay 87, back contact 01 the ringing key, ring con tacts of the plug and jack, lower conductor of the toll switching trunk, lower left hand winding 01 the repeating coil, right hand back contact and continuity spring of relay 1 and left hand winding; of relay 1 to ground. Since relay 8'? is of comparatively low rcsistance, relay 1 will be operated and in turn closes a circuit for oyiicrating relay 3, which circuit extends from grounded battery winding of relay 3 and make contact of relay 1 to ground.

The operation of relay 8 closes a circuit for operating relay 4:, said circuit extending from grounded battery, left hand winding of relay 1, upper, middle back Contact and armature of relay 12, inner left hand make contact of relay 3, inner, upper back con tact of relay 11 and make contact of relay 1 to ground. The operatlon of relay 4 opens the original operating c1rcu1t of relay 1, and establishes a substitute circuit for holding relay 1, from ground, left hand make contact and continuity spring of relay 4., and right hand winding of relay 1 to relay 11 and right hand winding of relay 18 to ground. This circuit is eilective to operate relay 18, which in turn closes a circuit from ground, flashing interrupter 4.3. make contact of relay 18, and both windingi of relay 19 in series, to grounded battery. The constantly operating inte"rupter con tact 43 causes the operation and release of relay 19 and this relay closes a circuit from ground, make contacts of: relay 19, left 1 winding of relay 18, to the circuit leading to lamp INC, previously traced. Since the right hand winding of relay 18 has a resistance comparatively high, for example two thousand ohms, it will be noted that lamp INC. will not receive sufficient current to be lighted, but relay 18 will receive sutl? cient current to be operated, as above described. The left hand winding of relay 18 is of comparatively low resistance, for example iive ohms, so that the closure of the circuit to ground at make contacts of relay 19, stablishes a low resistance shunt about the right hand winding of relay 18, which will allow suilicient current to flow for lighting lamp 1N C. It will. thus be seen that relay 19 will be intermittently operated as long as there is any connection established in this group 01 trunks to which relay 19 is common and that during its i"-terinittent operation relay 18 will be held energized and lamp INC. will be flashed, thus giviino; an '.-idication to the terminating operator, that a connection is established with the trunk with which lamp INC. is associated.

When the terminating operator ready to handle the connection associated with this trunk, she momenta 'ly den is the ass ment or cut'in key C. thereby closing a circuit from grounded battery, *inding of relay 20, back contacts of relay 2. ,1 left hand winding of relay 10, back contact 1-4 of relay 9, contact of key C. 1., upper back contact o'lf relay 12, left hand back contact of relay 9 and right hand middle make contact of relay 3 to ground. Relays 20 and 10 are operated in the above described circuit, a'ftcr which a circuit is established from grounded battery, winding of relay 21, inner right hand make contact and right hand winding of relay 10, upper back contact of relay 12, left hand back contact ofrelay 9 and right hand middle make contact of relay 3 to ground. This circuit is eilective to operate relay 21, which operation opens the original operating circuit of relays and I 10, but a substitute circuit for relay 10 is now established through its right hand winding. The operation of relay 20 as alnive described, connects the call-passing tone GPT to the operators common telephone circuit OPER. The complete operators talking circuit is not shownin this drawing, since it is of a well known type, for example as shown in the lower left hand portion of -Fig. 3 of my empending application above mentioned. The application oi this callpas ing tone to the operators talking circuit is for the purpose of notifying the originating toll operator that she is in telephonic connection with the terminating operators telephone set. This call-passing tone is extended by way of the two left hand make cont-acts of relay 10 through the right hand windings of the repeating coil and the windings of relay 2 to ground and grounded battery. The tone is repeated into the left hand windings of the repeating coil and thence by way of the two-wire trunk to the originating opcrators telephone set, which is connected.

to this trunk.

The operation of relay 21 as above described is for the purpose of includingthe high resistance winding of coil 22 in the common lead extending to all of the operator cut-in relays, similar to relay 10. This is for the purpose of preventing the oper ation of more than one relay, similar to relay 10 in case the operator should press another key similar to C. 1. associated with another trunk in this group, thus preventing the connection of the call passing tone and the operators talking circuit to more than one trunk at a time.

Shortly aifter the operation of relay 21 above pointed out relay 20 will release,'

since it does not get suliicient current hrough the winding of coil 22 to hold it in its energized condition. Relay 20,- therefore, remains operated only for a short in tcrval of time for the purpose of applying a shortsignal to the trunk for notifying the originating toll operator that the wanted number may be repeated, since the terminatin; operator is on the connection.

The incoming lamp INC is now dimly lighted, instead of being flashed as before, since relay 10 at its right hand middle contact opens the flashing circuit for this lamp and closes a circuit through the right hand make contact of relay 20 and the winding of relay 23 to ground. Relay 28 is or the proper resistance, for example two hundred ohms, to allow suiiicient current to flow through the lamp circuitto cause it to be.

operating relay 25.

only dimly lighted. Relay 23 is operated in series with the lamp and closes a circuit by way of its left hand make contact for After receiving the call-passing tone the toll operator repeats or passes the number of the wanted telephone line to the terminating or B operator. The B operator then makes the busy test of the wanted line and in this case where it is assumed that the jack T is associated with the desired telephone'line, she touches the tip of plug P of the trunk to the sleeve of jack T. H this line is busy, the B operator will hear a distinctive click in her telephone head set, which is a signal that the call cannot be completed. The circuit for giving this click extends from battery, which will be found on the sleeve of the jack ota busy line, tip of plug P upper back contact of relay 7, inner left hand make Contact of relay 10 to one side of the operators common telephone circuitand through circuits of the operators telephone set in the Well known manner for producing a distinctive click in her head set.

The operator upon hearing this busy indication depresses one of the busy-back keys BB to transmit a lousy-back signal to the calling subscriber. It will be noted that two busy-back keys are shown by which it is intended to indicate that two of these keys are placed on each operators position. One of the keys is placed at the right of the operators position and the other key is placed at the left, so that one of them is easily accessible to either hand of the operator. The operation of the busy-back key closes a circuit trom ground, make contact of the key, winding of the slow releasing relay 26 togrounded battery. delay 26 operates and completes a circuit from ground at its make contact, outer right hand armature and front contact of relay 10, lower, inner back contact of relayv 11 and winding of relay 12 to grounded battery. This operates relay 12 and it closes a locking circuit for itself extending from grounded battery, Winding or relay 12, up'

per, middle make contact oi relay 12, inner left hand make contact ofrelay 3, inner, upper back contact of relay 11 and make contact of relay 1 to ground. With relay 12 operated, a source of busy tone current BZ is connected to the right hand windings of the repeating cell by way 01. contacts and 46 of relay 12. One side of this busy tone current is connected through a noninductive winding placed on relay 18, in order to reduce the intensity 01"- the tone, so that it will be pleasing to the ear. This tone is induced intothe left hand winding of the repeating coil and from there leads back to the calling substation, which is connected to this trunk.

The operation of relay 12 opens at its extreme upper back contact, the circuit of relay and this latter relay releases, thus disconnecting the operators talking circuit hand back contact of relay 23, make contact of relay and winding of meter 24 to grounded battery, which functions to operate the meter and after a short interval relay 25 releases and opens the circuit of meter 24. The operation of this meter indicates that the B operator has completed her work in connection with one call.

The deenergizat-ion of relay 10 opens at its right hand middle make contact-the circuit of the lamp INC, thus extinguishing this signal. The operation of relay 12 opens at its upper middle back contact, the circuit of the left hand winding of relay 4, which allows this latter relay to release. At both back contacts and continuity springs of rolay 4, the circuit of relay 1 is reestablished to the left hand windings of the repeating coil and relay 1 is maintained in its energized position, by means of the closed circuit across the. toll switching trunk. The circuit to ground and grounded battery through the windings of relay 1 is effective to operate relay 3'? in the toll cord circuit and the battery relay closes a circuit for lighting supervisory lamp 42.

The operation of relay 12 closes a circuit extending from grounded battery, lower winding of relay 2, lower, right hand w1nding of the repeating coil, contact 46 of relay 12, right hand winding of relay 13 and left hand winding of relay 15 to ground. The left hand winding of relay 15 is of very high resistance, for example five thousand ohms, this being of sufiicient resistance to prevent the operation of relay 2 over this circuit, but relay 15 will be energized and will close a circuit from the common busy-back flashing interrupter 47 for operating relay 16. The

operation of relay 16 connects the right hand winding of relay 15 by way of contacts and 46 of relay 12 across the outside terminals of the right hand winding of the repeating coil and since the right hand winding of relay 15 is of comparatively low resistance, for example fifty ohms, this bridge across the right hand winding of the repeating coil will cause relay 2 to be operated. /Vhen interrupter 4'? opens its contact, relay 16 is released and this low resistance shunt, consisting of the right hand winding of relay 15, is removed until contact 47 is again closed, this operation functioning to cause relay 2 to be intermittently operated. The intermittent closingand opening of the make contact on relay 2 closes a circuit from ground, right hand middle contact of relay 3, make contact of relay 2 and right hand Winding of relay 4 to grounded battery, which circuit functions to cause the intermittent operation of relay 4. Relay 4 thereby opens and closes the battery bridge of relay 1 to the toll switching trunk, leading back to the toll position and this opening and closing of the battery circuit on this trunk causes relay 3'? to intermittently operate and flash the lamp 42. This is for the purpose of giving the toll operator a Visual indication that the called line is busy at the same time that the busy-back tone is being applied to the calling line.

Let it be, assumed that at the time the test of the wanted line is made, this line is found to be idle, whereupon the l3 operator insertsthe plug P into the jack T of the wanted line and assuming that the wanted line is a party line, the operator depresses some one of the stations keys lo cated in the lower right hand portion of Fig. 2, to connect the proper source of ringeurrent tothe toll switching trunk with which to ring the desired station on the wanted line. With the plug P in engagement with jack T the cut-off relay 32 and the sleeve relay 8 are energized. The energization of relay '32 is for the well known purpose of removing the line relay 33 from across the called line circuit. The operation of relay 8 closes a circuit for operating relay 5 extending from grounded battery, winding of relay 5, inner, right hand back contact of relay 9 and make contact of relay 8 to ground. Lamp INC. now burns dimly as an indication to the B operator that the circuit has been established to the wanted line, but that the ringing frequency has not been selected. The circuit for dimly lighting lamp INC. has been previously described.

Assuming that the wanted station E has a ringer which responds to the source of fifty cycle ringing current, the operator depresses the ringing key marked fifty cycles, which results in the energization of the slow releasing relay 28. This relay thereupon attracts its armatures to complete an operatlng circuit for relay 14, extending from grounded battery, winding of relay 14, lower outer make contact of relay 5 and inner make contact of relay 28 to ground. Relay 14 as soon as it is operated, closes a locking circuit for itself from grounded battery, through its winding and inner left hand make contact and make contact of relay 8 to ground. Also at this time relay 9 is energized in acircuit extending from grounded battery winding of relay 9, inner, upper make contact of relay 5 and outer make contact of relay 28 to ground. Relay 9 closes a locking circuit for itself extending from grounded battery, its'winding, inner, right and make contact and. make contact of re lay 8 to ground. A circuit is also closed for operating relay 11, extending from grounded battery, lower winding of this relay, up ier make contact of relay 5 and left hand make contact of relay 28 to ground. Relay 11 closes a locking circuit for itself extending from grounded battery, lower winding of relay 11, lower make contact of relay 11 enter right ha d make contact of relay 3 and make contact oi relay 8 to ground. The operation of relay 9 opens the circuitsot both windings of relay 10, this latter relay releases and by opening its right hand middle make contact extinguishes the lamp INC. The lamp INC. is connected by way of a back contact of relay 10 to a circuit including the right hand inner ma is contact oi relay 3, but this circuit is interrupted at the upper, outer back contact of relay 11. The release of relay 10 as above described functions to release relays 23 and 25 and to operate meter 24in a manner which was previously described in connection with a call for a busy line. i

The operation. of relay scribed, opens at its inner, right hand back contact the circuit of relay 5 and this latter relay deenergizes, opening the previouslv es- 9, as above detablished circuits for. ringin selecting relays 13 and 14. The operation of relay 11, as above described, opens at its upper, inner back contact, the circuit of the left hand 4: and this relay deenergizes, placing relay 1 across the trunk leading hack to the toll cord circuit. The circuit to ground and grounded battery through relay 1, across this trunk functions to operate relay 37 of the toll cord circuit and. this latter relay closes a circuit for lighting the supervisory lamp 42. i

From the above description, it will be seen that the proper ringing frequency, in this case fifty. cycles, has been selected by the terng inating or B operator and this ring ing frequency has been extended through the outer left hand make contact of relay 14,- and the outer hack contact of relay 13 to the lower make contact of relay 7. The ringing current is not applied to the called line in this system, until the toll operator rings over the toll switching trunk. TV hen the toll operator is ready to establish the connection, she operates her ringing key, which is effective to apply generator and ground to the two sides of the toll switching trunk. key opens the circuit to relay 37 during the ringing interval and to prevent pren'iature release of relay 1, which controls the connection at this time, a bridge consisting; of impedance coil 40 is maintained across the trunk, during. the ringing period because the sleeve circuit ot the toll calling cord is not interrupted. The ringing current, entendsthrough the lctthandwindings ofthe winding of relay It will be noted that the ringing.

side of the called line, tip contacts of the plug and ack and the upper make contact of relay 7 to ground. This ringing current is only applied during the time that the toll operator actuates her ringing key, therefore, the called subscriber understands that this is a toll call, because the bell is not actuated by the automatic ringing equipment,

lV hen the called party answers, a circuit is closed from grounded battery, lower winding of relay 2, lower, right hand winding of the repeating coil, lower back contact of relay 7, ring ofthe plug and jack over the called line circuit, tip of the plug and jack, upper back contact of relay 7, upper, right hand winding of the repeating coil and the upper winding of relay 2 to ground. Talking battery issupplied to the called line over the above traced circuit and relay 2 is energized, closing a circuit for operating relay l extending from grounded battery. right hand winding of relay 4, make contact ofrelay 2 and right hand middle make con: tact of relay 3 to ground. The operation of relay removes the bridge to ground and rounded battery through relay 1, which runctions to release relay 37 in the toll cord circuit, thus extinguishing lamp 42, this being an indication that the called party has answered. Talking battery for the cal ing substation is supplied from local, batteries at this substation.

At the close of the conversation when the called party hangs up the receiver, relay 2 retracts its armature, which opensthe circuit of the right hand winding of relay 4%. This relay releases and again applies the battery bridge through the windin of relay 1 to the toll cord circuit by way of the toll switching trunk. RelayST is new energized closing a circuit for lighting supervisory lamp .2 as an indication to the toll operator that the called party has disconnected.

The toll operator now supervises the connection and stamps the toll ticket. after which she removes the plug P from iackT. This removes the bridge consisting" of relav 37 and relay 3!) releases, removing the bridge consisting of coil 10 from the toll switching trunk. This functions to release relay 1 and this latter relay at its make contact opens the circuit of relay 3, releasing this latter relay. A circuit is now established for lighting lamp INC, which at this time serves as a disconnect .signal for the toll switching operator. This circuit extends from grounded battery, lamp, right hand middle back contact of rela 10 lower back contact .V a

of relay 12, right hand, inner back contact of relay iland make contact of relay 8 to ground. The B operator thereupon removes the plug P from jack T thus releasing relays 32 and 8. The release of relay 8 opens the loc ring circuits of relays 9 and 14 and the release of relay 3, as above described, opens the locking circuit of relay 11.

If, during the time of extremely light trailic through the exchange, for instance late at night, the B operator is not at the position when the toll operator disconnects from the switching trunk, as above described, when relay 3 is released a circuit is established from ground, make contact of relay 8, outer, left hand back contact of relay 3' and winding of common relay 17 to grounded battery. This latter relay is energized and closes a circuit for actuating an alarm signal indicated at 4-8. When the B operator removes the plug from jack T and relay 8 is released. the circuit for actuating this night alarm is interrupted.

The apparatus is now in its normal condition, in readiness for use in a. succeeding call.

It sometimes happens that the B oper ator desires to connect a toll switching trunk with another circuit without the necessity of selecting a ringing frequency. Such a men tioned connection may arise when it is necessary to xtend a connection from the trunk circuit to an intercepting operator. In such a case it is necessary for the B operator to cause the circuit to function to apply ground to the two make contacts of relay 5 by way of conductor 50. Of course, it would only be necessary to operate someone of the frequency selecting buttons, thereby energizing one of the relays 27, 28. 29 or 30, but in order to make the operation uniform, so that a B operator from some other position in the exchange can-handle the toll switching position without any change in the method of operation, the non-ring key NR has been provided. The operation of key NR energizes relay 31 and it in turn connects ground through the make contacts of relay 5 for energizing and locking relays 11 and 9. This places the circuit in the same condition as in the previously described connection just after the operator depressed the 50 cycle button.

It sometimes happens that the toll operator momentarily opens the circuit of the switching trunk at the plug P In such a case, relays 1 and 11 would be released and lamp INC. would begin to flash. The l operator now presses the cutin key C. I. to re-establish connection with this circuit,

thereby closing a circuit from grounded outer make contact of relay 9, right hand, 5

inner make contact of relay 9 to ground at a make contact of relay 8. Belay 11 is operated over this circuit and relay 10 is energized by way of its right hand winding for connecting in the common equipment including the operators talking circuit. In this case, however, since relay 10 is operated by way of its right hand winding, relay 20 will not be energized with the result that the call-passing tone will not be applied to the trunk and since relay 23 will not be operated. the meter will not record another completed call. for a connection of this kind.

What I claim is:

1. In a telephone system, a'calling line and a called line, means including a cord circuit and trunk circuit for interconnecting said lines, an o'perators telephone set, means responsive to the extension of said calling line to said trunk circuit for connecting said operators telephone set to said trunk circuit to the exclusion of other trunk circuits, means for extending said trunk circuit to said called line, a plurality of sources of ringing current for s1gnalling stations on said called line, means including a sin 'le ringing key for each source of ringing current common to a plurality of said trunk circuits, means responsive tothe depression of one of said ringing keys for selecting the proper source of signalling current to signal the wanted station on said called line, and means controlled from said cord circuit for applylng said proper source ofsignalling current to said called line.

2. In a telephone system, a calling line and a called line, means including a cord circuit at a first position and a trunk circuit at a second position for interconnecting said lines, an operators telephone set, means responsive to the extension of said calling line to said trunk circuit for connecting said operators telephone set to said trunk circuit to the exclusion of other trunk circuits, means for extending said trunk circuit to said called line, a plurality of sources of ringing current for signalling stations on said called line, means including a single ringing key for each source of ringing current common to a plurality of said trunk circuits, means responsive to the depression of one of said ringing keys for selecting the proper source of signalling current to signal the wanted station on said called line, and means controlled at the will of the operator at said first position for applying said proper source of signalling current to said called line.

3. In a telephone system, a calling line and it called line, means including a cord circuit at :1 first position and a trunk circuit ata second posit-ion for interconnecting said lines, an operators telephone set, means responsive to the extension of said calling line to said trunk circuit for connecting said operators telephone set to said trunk circuit to the exclusion of other trunk circuits, means for extending said trunk circuit to said called line, plurality o sources of ringing current for signalling stations on said called line, means including a single ringing key for each source of ringing current common to a plurality of said trunk circuits, means responsive to the depression of one of said ringing keys for selecting the proper source of signalling current to signal the Wanted station on said called line, and means manually controlled at said cord circuit for applying said proper source of signalling current to said called line.

4. in a telephone system, a toll position and a local position, telephone lines terminating at each of said positions, certain oi said telephone lines being party lines having a plurality oi stations, runks forinterconnecting said positions, means at the toll position for extending a calling telephone line terminating thereat to a trunk, a signal lamp individual to said trunk, a circuittor lighting said lamp When said trunk is extending to a calling telephone line, anoperators telephone set, means controlled in part by the extension of said calling telephone line to said trunk for connecting said operators tel: ephone set to said trunk to the exclus on of other trunks, means including a portion of said first mentioned circuit for dimly lighting said lamp While said operators telephone set is connected to sa dtrunlr, means for extending said trunk to a Wanted telephone line, a plurality of sources of ringing current for signalling the stations on said party lines, means includinga single ringing key for each source of ringing current coinmon to said trunk circuits for selecting the proper source of signalling current to signal the Wanted station on said Wanted telephone line, and means controlled iroin said toll position for applying said proper source of signalling current to said Wanted telephone line.

5. in a telephone system, a toll position and a local position, telephone lines terminating at each of said positions, certain of said telephone lines being party lines having a plurality of stations, trunks for interconnectin said positions, means at the toll position Ior extending a calling telephone line terminating thereat to a trunk, a signal amp individualto said trunk, a circuit for light-- ing said lamp when said trunk is extended to a calling telephone line, an operator's tele phone set, means controlled in part hy the extension of said calling telephone line to said trunk for connecting said operators telcphone set to said trunk to the exclusion of other trunl s, means including a portion of said first mentioned circuit for lighting said lamp in a distinctive manner hile said opcrators telephone set is connected to said trunk, means for extending said trunk to a Wanted telephone line, a plurality of sources of ringing current for signalling the stations on said party lines, means including single ringing key for each source of ringing current common to said trunk circuits for Se leting the proper source of signalling currentto signal the Wanted station on said Wanted telephone line, and means controlled from said toll position for applying said proper source of signalling current to said wantedtelephone line.

6. In a telephone system, a toll-position and a local position, telephone lines terminating at each of said positions, means at the toll position for extending a callingvtelephone line terminating thereat to a trunk, an operators telephone set at the local position, automatic means responsive to the extension or" said calling telephone line to said trunk for connecting said opcrators tele phone circuit to said trunk to the exclusion of other trunks, means for signalling the operator at the toll position that such connection has been made, a plurality of sources of ringing current for signalling" stations terminating at said local position, means including a single ringing key for each source of ringing current common to said trunk circuits for selecting the proper source of signalling current to signal the Wanted station, and means manually controlled at the will of the operator at said toll position for applying said proper source of signalling current to said Wanted line.

7. In a telephone system; an originating position, a terminating position, telephone lines terminating at each of said positions, means at the originating position for extending a calling telephone line terminating thereat to a trunk, an operators telephone sot at the terminating position, a source of signalling current, a relay individual to each trunk for connecting said operators telephone set to said trunk and for connecting said signalling current to said trunk, automatic means responsive to the extension of said calling telephone line to said trunk for actuating said relay, a plurality of sources of ringing current for signalling stations on said Wanted telephone line, means common to a plurality of said trunks for selecting source of ringing current, and means controlled at the originating position for applying said source of signalling current to said Wanted telephone line.

8, In a telephone system, an originating position and a terminating position, telephone lines terminating at each of said positions, trunks each having conductors extending between said positions, means for extending telephone lines to each end of a trunk, a. plurality of sources of ringing current for signalling stations on telephone lines terminating at said terminating position, means including a single ringing key for each source of ringing current, said keys being common to a plurality of said trunks for selecting the propersource of ringingjg' current for signalling the Wanted station, a relay in said trunk circuit for connecting said selected ringing current to said Wanted line for signalling the Wanted station thereon, and means controlled at said originating position for energizing said relay.

9, In a telephone system, an originating position and a terminating position, tele phone lines terminating at each oil said po sitions, certain of said telephone lines being party lines having a plurality of stations, trunks for interconnecting said positions, means at the originating position for extending a calling telephone line terminating thereat to a trunk, a plurality oi? sources of ringing current for signalling the stations on said party lines, means including a single key for each source or ringing current, said keys being common to said terminating); position for selecting the proper source oi? rim;- ing current for signalling a Wanted station. on one of said party lines, a relay in said trunk circuit controlled by ringing current from said originating position tor applying said selected ringing current to one of saitv party lines for sign lling said Wanted station. l I

10. In a telephone system, an originating position and a terminating position, telephone lines terminating at each of said positions, trunk circuits extending; between said positions-,- means for extending telephone lines to each end of said trunk circuits, sources of signalling current for signalling stat-ions on telephone lines connected to said terminating position, a single key common to said trunk circuits for each sourceol signaling' current at said terminating position, a source of ringing current at said originatingz; position, a battery bridge acrosssaid trunk at said to minatini position, means for removing said battery bridge from across said trunk when saidringing current connected to said trunk at said originating position, and means controlled by said ringing current for applying to a Wantedstation on one of said telephone lines signaling current selected by the operation of one of said common keys.

In witness whereof, I hereunto subscribe my name this 21st day of December A. D.

JOHN H. LEVIS, JR. 

